Bronchoconstrictive disorders affect millions worldwide. Such disorders include asthma (including bronchial asthma, allergic asthma and intrinsic asthma, e.g., late asthma and airway hyper-responsiveness), chronic bronchitis and other chronic obstructive pulmonary diseases. Compounds having β2-adrenoreceptor agonist activity have been developed to treat these conditions. Such compounds include, but are not limited to, Albuterol (α1-(((1,1-dimethylethyl)amino)methyl)-4-hydroxy-1,3-benzenedimethanol); Bambuterol (dimethylcarbamic acid 5-(2-((1,1-dimethylethyl)amino)-1-hydroxyethyl)-1,3-phenylene ester); Bitolterol (4-methylbenzoic acid 4-(2-((1,1-dimethylethyl)amino)-1-hydroxyethyl)-1,2-phenylene ester); Broxaterol (3-bromo-α-(((1,1-dimethylethyl)amino)methyl)-5-isoxazolemethanol); Isoproterenol (4-(1-hydroxy-2-((1-methylethyl)amino)ethyl)-1,2-benzenediol); Trimetoquinol (1,2,3,4-tetrahydro-1-((3,4,5-trimethoxyphenyl)methyl)-6,7-isoquinolinediol); Clenbuterol (4-amino-3,5-dichloro-α-(((1,1-diemethylethyl)amino)-methyl)benzenemethanol); Fenoterol (5-(1-hydroxy-2-((2-(4-hydroxyphenyl)-1-methylethyl)-amino)ethyl)-1,3-benzenediol); Formoterol (2-hydroxy-5-((1RS)-1-hydroxy-2-(((1RS)-2-(p-methoxyphenyl)-1-methylethyl)amino)ethyl)formanilide); (R,R)-Formoterol; Desformoterol ((R,R) or (S,S)-3-amino-4-hydroxy-α-(((2-(4-methoxyphenyl)-1-ethylethyl)amino)methyl)-benzene-methanol); Hexoprenaline (4,4′-(1,6-hexanediyl)-bis(imino-(1-hydroxy-2,1-ethane-diyl)))bis-1,2-benzenediol); Isoetharine (4-(1-hydroxy-2-((1-methylethyl)amino)butyl)-1,2-benzenediol); Isoprenaline (4-(1-hydroxy-2-((1-methylethyl)amino)ethyl)-1,2-benzenediol); Metaproterenol (5-(1-hydroxy-2-((1-methylethyl)amino)ethyl)-1,3-benzenediol); Picumeterol (4-amino-3,5-dichloro-α-(((6-(2-(2-pyridinyl)ethoxy)hexyl)-amino)methyl)benzenemethanol); Pirbuterol (α6-(((1,1-dimethylethyl)amino)methyl)-3-hydroxy-2,6-pyridinemethanol); Procaterol (((R*,S*)-(±)-8-hydroxy-5 (1-hydroxy-2-((1-methylethyl)amino)butyl)-2(1H)-quinolinone); Reproterol ((7-(3-((2-(3,5-dihydroxy-phenyl)-2-hydroxyethyl)amino)propyl)-3,7-dihydro-1,3-dimethyl-1H-purine-2,6-dione); Rimiterol (4-(hydroxy-2-piperidinylmethyl)-1,2-benzenediol); Salbutamol ((±)-α1-(((1,1-dimethylethyl)amino)methyl)-4-hydroxy-1,3-benzenedimethanol); (R)-Salbutamol; Salmeterol ((±)-4-hydroxy-α1-(((6-(4-phenylbutoxy)hexyl)amino)methyl)-1,3-benzenedimethanol); (R)-Salmeterol; Terbutaline (5-(2-((1,1-dimethylethyl)amino)-1-hydroxyethyl)-1,3-benzenediol); Tulobuterol (2-chloro-α-(((1,1-dimethyl-ethyl)amino)-methyl)benzenemethanol); and TA-2005 (8-hydroxy-5-((1R)-1-hydroxy-2-(N-((1R)-2-(4-methoxyphenyl)-1-methylethyl)amino)ethyl)carbostyril hydrochloride).
These compounds are typically formulated for inhalation therapy. Aqueous or liquid formulations are preferred over solid formulations. Powdered formulations are more difficult to administer, particularly to the young and elderly who are most often the patients in need of such therapy. Compounds, such as formoterol are not adequately stable in aqueous solutions to be formulated as liquids. Hence there is a need for formulations of compounds, such as formoterol, in a form that can be conveniently administered and that are stable for extended periods of time.